1. Field of the Invention
The present invention relates to a feed-through, and, more particularly, to a feed-through through a housing part of a housing for example of a storage device, for example a battery or a capacitor made of metal, in particular a light metal, for example aluminum or an aluminum alloy, AlSiC, magnesium, a magnesium alloy, titanium, a titanium alloy, steel, stainless steel or high grade steel, and a housing for an electric storage device, for example a battery or a capacitor having such a feed-through, and a storage device such as a capacitor with a housing according to the invention.
2. Description of the Related Art
Storage devices such as batteries are understood to be disposable batteries which are disposed of and/or recycled after discharge, as well as accumulators. Accumulators, preferably lithium-ion batteries are intended for various applications, for example for portable electronic equipment, cell phones, power tools and in particular electric vehicles. The batteries can replace traditional energy sources, for example lead-acid batteries, nickel-cadmium batteries or nickel-metal hydride batteries.
Lithium-ion batteries have been known for many years. For example, as described in the “Handbook of Batteries, published by David Linden, 2nd issue, McGrawhill, 1995, chapter 36 and 39”.
Various aspects of lithium-ion batteries are described in a multitude of patents, for example U.S. Pat. Nos. 961,672, 5,952,126, 5,900,183, 5,874,185, 5,849,434, 5,853,914 as well as 5,773,959.
Lithium-ion batteries, in particular for applications in the automobile industry generally feature a multitude of individual battery cells which are generally connected in-series. The in-series connected battery cells are combined into so-called battery packs and several battery packs are then combined into a battery module which is also referred to as lithium-ion battery. Each individual battery cell has electrodes which are led out of a housing of the battery cell.
In the use of lithium-ion batteries in the automobile industry, a multitude of problems such as corrosion resistance, stability in accidents or vibration resistance must be solved. An additional problem is the hermeticity over an extended period.
The hermeticity may, for example, be compromised by leakage in the area of the electrodes of the battery cell or respectively the electrode feed-through in the battery cell. Such leakages may, for example, be caused by temperature changes and alternating mechanical stresses, for example vibrations in the vehicle or aging of the synthetic material.
A short-circuit or temperature change in the battery or respectively battery cell can lead to a reduced life span of the battery or the battery cell.
To ensure better stability in accidents, a housing for a lithium-ion battery is suggested, for example, in DE 101 05 877 A1, whereby the housing includes a metal jacket which is open on both sides and which is being sealed.
The power connection or respectively the electrodes are insulated by plastic. Disadvantages of plastic insulation may include the limited temperature resistance, the limited mechanical stability, aging and the uncertain hermeticity over the service life.
The feed-throughs in the lithium-ion batteries according to the current state of the art are therefore not integrated hermetically sealed into the cover part of the lithium-ion battery. At a pressure difference of 1 bar, a helium leakage rate of max. 1·10−6 mbar 1 s−1, dependent upon inspection specification, is normally attained in the current state of the art. Moreover, the electrodes are crimped and laser welded connecting components with additional insulators are arranged in the interior of the battery.
Feed-throughs are known from WO 2012/167921, WO 2012/110242, WO 2012/110246, WO 2012/110244 that lead through a housing part of a housing for a storage device. In the feed-throughs, a cross section in a glass or glass ceramic material is guided through the opening.
When used in a storage device, two feed-throughs with conductors are provided as a general rule, namely at least one conductor that serves as a cathode and at least one additional conductor that serves as an anode of the electrochemical cell. The materials of the anode or respectively the cathode differ from one another. Copper or a copper alloy is used for the pin type conductor, if the pin type conductor is being connected to a cathode of the electrochemical cell or battery cell and aluminum (Al) or an aluminum alloy is used, if the conductor is being connected to an anode. Other materials are also possible, as described in WO 2012/167921, the disclosure content of which is included into the current application in its entirety.
With the electrochemical cell in WO 2012/167921 the problem exists, that the outside connection of the storage device or respectively the battery cell includes two different materials which can be detrimental, particularly when connecting several battery cells with each other.
EP 2 371 419 A2 illustrates an electric feed-through of a capacitor for medical implants, as well as methods for production and use of the same. It is described in EP 2 371 419 A2 that the connecting pin consists of two pin sections; a first pin section consisting of Pt, Pt/Ir, FeNi, FeNiCo, FeCr, Nb, Ta, Mo, W, Cr, FeCr, V or Fi and a second pin section that includes aluminum. However, Cu is not mentioned in EP 2 371 419 A2 as a material for the first pin section. Moreover, no values for the thermal coefficient of expansion α are stated in EP 2 371 419 A2. In addition, a hermetically sealed feed-through cannot be achieved with the glasses specified in EP 2 371 419 A2, because the thermal expansion of the glasses is too small for this.
DE 10 2013 006 463 describes a feed-through for a battery, such as a lithium-ion battery. However, the pin-shaped conductor consists of one single material.
What is needed in the art is a feed-through that avoids the problems of the current state of the art.